Method for improving deposit control and cleanliness performance in an engine lubricated with a lubricating oil

ABSTRACT

wherein [Gn] is the weight percent of each of n dispersants in the formulated oil, [Bm] is the weight percent of each of m viscosity modifiers in the formulated oil, dV/d[Gn] is the kinematic viscosity (Kv100) increase of the lubricating oil per the weight percent of each of n dispersants in the formulated oil, and dV/d[Bm] is the kinematic viscosity (Kv100) increase of the lubricating oil per the weight percent of each of m viscosity modifiers in the formulated oil.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 62/535,433, filed on Jul. 21, 2017, the entire contents of which are incorporated herein by reference.

FIELD

This disclosure relates to a method for improving deposit control and cleanliness performance in an engine lubricated with a lubricating oil. This disclosure also relates to a lubricating oil having a lubricating oil base stock as a major component, and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components. This disclosure further relates to a method for tuning deposit control and cleanliness performance in an engine lubricated with a lubricating oil, from poor to excellent deposit control and cleanliness performance.

BACKGROUND

Lubricating oils for internal combustion engines contain in addition to at least one base lubricating oil, additives which enhance the performance of the lubricating oil. A variety of additives such as detergents, dispersants, friction reducers, viscosity modifiers, antioxidants, corrosion inhibitors, antiwear additives, pour point depressants, seal swell additives, and antifoam agents are used in lubricating oil compositions.

During engine operation, oil insoluble oxidation byproducts are produced. Dispersants help keep these byproducts in solution, thus diminishing their deposit on metal surfaces. Dispersants may be ashless or ash-forming in nature. So called ashless dispersants are organic materials that form substantially no ash upon combustion.

A known class of dispersants is the alkenylsuccinic derivatives, typically produced by the reaction of a long chain substituted alkenyl succinic compound, usually a substituted succinic anhydride, with a polyhydroxy or polyamino compound. The long chain group constituting the oleophilic portion of the molecule which confers solubility in the oil, is normally a polyisobutylene group. Many examples of this type of dispersant are well known commercially and in the literature.

Viscosity modifiers are also used in lubricating oil compositions. These additives provide lubricants with high and low temperature operability, and impart shear stability at elevated temperatures and acceptable viscosity at low temperatures. Viscosity modifiers are well known commercially and in the literature.

Engine cleanliness is a critical performance attribute of modern engine lubricants. A well known engine cleanliness test is a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure. This cleanliness test is a performance defining test which is required for all engine lubricants carrying ACEA certification.

Formulations that fail the CEC L78-T-99 test procedure are typically reformulated in an attempt to find the particular base oil and additive concentrations needed to pass the CEC L78-T-99 test procedure. This reformulation effort can be quite cumbersome and complicated.

It would be desirable to reduce the formulation complexity needed to find the particular base oil and additive concentrations required to pass the CEC L78-T-99 test procedure. In particular, it would be desirable to reduce the formulation complexity needed to maintain acceptable to strong cleanliness, as determined by the CEC L78-T-99 test procedure, to a single parameter threshold.

The present disclosure also provides many additional advantages, which shall become apparent as described below.

SUMMARY

This disclosure relates to a method of using a critical dispersant thickening ratio to improve the deposit controlling properties and cleanliness performance of engine lubricants. The critical dispersant thickening ratio is effectively the ratio of the thickening efficiency contribution of the dispersant to the thickening efficiency contribution of the viscosity modifier. The critical dispersant thickening ratio provides a simple method of determining whether the deposit controlling properties and cleanliness performance would be considered acceptable. The critical dispersant thickening ratio can also be used to tune deposit control and cleanliness performance, and improve cleanliness in a formulation which fails the CEC L78-T-99 test procedure.

In particular, this disclosure relates in part to a method for improving deposit control and cleanliness performance in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil comprises a lubricating oil base stock as a major component, and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components. The at least one dispersant and the at least one viscosity modifier are present in an amount sufficient to have a critical dispersant thickening ratio of greater than about 0.33. The critical dispersant thickening ratio is determined in accordance with the formula:

$\frac{{\Sigma \left\lbrack G_{n} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack G_{n} \right\rbrack}}{{\Sigma \left\lbrack B_{m} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack B_{m} \right\rbrack}}$

wherein [Gn] is the weight percent of each of n dispersants in the formulated oil, [Bm] is the weight percent of each of m viscosity modifiers in the formulated oil, dV/d[Gn] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of n dispersants in the formulated oil, and dV/d[Bm] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of m viscosity modifiers in the formulated oil.

Further, in particular, this disclosure also relates in part to a lubricating oil comprising a lubricating oil base stock as a major component, and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components. The at least one dispersant and the at least one viscosity modifier are present in an amount sufficient to have a critical dispersant thickening ratio of greater than about 0.33. The critical dispersant thickening ratio is determined in accordance with the formula:

$\frac{{\Sigma \left\lbrack G_{n} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack G_{n} \right\rbrack}}{{\Sigma \left\lbrack B_{m} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack B_{m} \right\rbrack}}$

wherein [Gn] is the weight percent of each of n dispersants in the formulated oil, [Bm] is the weight percent of each of m viscosity modifiers in the formulated oil, dV/d[Gn] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of n dispersants in the formulated oil, and dV/d[Bm] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of m viscosity modifiers in the formulated oil.

Yet further, in particular, this disclosure also relates in part to a method for tuning deposit control and cleanliness performance in an engine lubricated with a lubricating oil. The method comprises using as the lubricating oil a formulated oil, in which the formulated oil comprises a lubricating oil base stock as a major component, and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components; and adjusting the amount of the at least one dispersant and the at least one viscosity modifier sufficient to provide a determined critical dispersant thickening ratio. The critical dispersant thickening ratio is determined in accordance with the formula:

$\frac{{\Sigma \left\lbrack G_{n} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack G_{n} \right\rbrack}}{{\Sigma \left\lbrack B_{m} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack B_{m} \right\rbrack}}$

wherein [Gn] is the weight percent of each of n dispersants in the formulated oil, [Bm] is the weight percent of each of m viscosity modifiers in the formulated oil, dV/d[Gn] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of n dispersants in the formulated oil, and dV/d[Bm] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of m viscosity modifiers in the formulated oil.

In an embodiment, the amount of the at least one dispersant and the at least one viscosity modifier is sufficient to provide a critical dispersant thickening ratio of greater than about 0.33 in a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure.

It has been surprisingly found that a critical dispersant thickening ratio can be employed to tune a lubricant formulation from poor to excellent cleanliness performance based solely on the critical dispersant thickening ratio, regardless of other additives/chemistry included in the lubricant formulation.

Also, it has been surprisingly found that reformulation complexity previously needed to maintain acceptable to strong cleanliness in an engine lubricated with a lubricating oil, as determined by the CEC L78-T-99 test procedure, can be reduced to a single parameter threshold, namely the critical dispersant thickening ratio.

Further objects, features and advantages of the present disclosure will be understood by reference to the following drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 graphically shows a plot of an engine cleanliness test, namely a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure (y axis) and critical dispersant thickening ratios (x axis), in accordance with the Examples.

FIG. 2 shows lubricating oil formulations prepared in accordance with the Examples, and also testing results from the formulations in accordance with the Examples.

DETAILED DESCRIPTION

All numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

In accordance with this disclosure, a method of using a critical dispersant thickening ratio to improve the deposit controlling properties and cleanliness performance of engine lubricants is provided. The critical dispersant thickening ratio is effectively the ratio of the thickening efficiency contribution of the dispersant to the thickening efficiency contribution of the viscosity modifier. The critical dispersant thickening ratio provides a simple method of determining whether the deposit controlling properties and cleanliness performance would be considered acceptable. The critical dispersant thickening ratio can also be used to tune deposit control and cleanliness performance, and improve cleanliness in a formulation which fails the CEC L78-T-99 test procedure.

Also, in accordance with this disclosure, the critical dispersant thickening ratio is determined in accordance with the formula:

$\frac{{\Sigma \left\lbrack G_{n} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack G_{n} \right\rbrack}}{{\Sigma \left\lbrack B_{m} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack B_{m} \right\rbrack}}$

wherein [Gn] is the weight percent of each of n dispersants in the formulated oil, [Bm] is the weight percent of each of m viscosity modifiers in the formulated oil, dV/d[Gn] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of n dispersants in the formulated oil, and dV/d[Bm] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of m viscosity modifiers in the formulated oil.

Further, in accordance with this disclosure, cleanliness performance can be assessed by calculating the critical dispersant thickening ratio. For example, for each dispersant [Gn] in the formulated oil, multiply [Gn] by dV/d[Gn], and sum overall all n of these contributions: Σ[Gn]*dV/d[Gn]. Then, for each viscosity modifier [Bm] in the formulated oil, multiply [Bm] by dV/d[Bm], and sum over all m of these contributions: Σ[Bm]*dV/d[Bm]. Then, take the critical dispersant thickening ratio of Σ[Gn]*dV/d[Gn] over Σ[Bm]*dV/d[Bm], and add dispersant and/or remove viscosity modifier from the formulated oil if the critical dispersant thickening ratio is less than 0.33, and a superior passing CEC L78-T-99 test result is desired.

In an embodiment, the amount of the at least one dispersant and the at least one viscosity modifier is sufficient to provide a critical dispersant thickening ratio of greater than about 0.33 in a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure.

In another embodiment, the critical dispersant thickening ratio is greater than about 0.33, or greater than about 0.40, or greater than about 0.47, or greater than about 0.50, or greater than about 0.60, or greater than about 0.70, or greater than about 0.75, or greater than about 0.80, or greater than about 0.90, or greater than about 1.0.

In yet another embodiment, the critical dispersant thickening ratio can be used to improve mid-SAPS (sulfated ash, phosphorus and sulfur) light duty engine oil performance in a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure.

Illustrative lubricating oil base stocks useful in this disclosure include, for example, Group I base stocks, Group II base stocks, Group III base stocks, Group IV base stocks, Group V base stocks, or mixtures thereof. Illustrative lubricating oil base stocks useful in this disclosure are described more fully hereinbelow.

Illustrative dispersants useful in this disclosure include, for example, hydrocarbyl-substituted succinic acid derivatives, hydrocarbyl-substituted succinic anhydride derivatives, succinimides, succinate esters, succinate ester amides, Mannich base adducts derived from a hydrocarbyl-substituted phenol condensed with an aldehyde and an amine, hydrocarbyl-substituted amines, polymethacrylate or polyacrylate derivatives, and the like. Preferably, the dispersant is an ashless dispersant. Illustrative dispersants useful in this disclosure are described more fully hereinbelow.

Illustrative viscosity modifiers useful in this disclosure include, for example, linear or star-shaped polymers and copolymers of methacrylate, butadiene, olefins, alkylated styrenes, and the like. Illustrative viscosity modifiers useful in this disclosure are described more fully hereinbelow.

In an embodiment, the lubricating oil can have other additives, for example, an antioxidant, detergent, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive. Illustrative additives useful in this disclosure are described more fully hereinbelow. In accordance with this disclosure, the critical dispersant thickening ratio can be employed to tune a lubricant formulation from poor to excellent cleanliness performance based solely on the critical dispersant thickening ratio, regardless of other additives/chemistry included in the lubricant formulation.

In another embodiment, the lubricating oil base stock is present in an amount from about 78 weight percent to about 98 weight percent, the dispersant is present in an amount from about 0.5 weight percent to about 12 weight percent, and the viscosity modifier is present in an amount from about 0.5 weight percent to about 10 weight percent, based on the total weight of the lubricating oil. As described herein, the amount of the dispersant and the viscosity modifier can be adjusted so as to tune the critical dispersant thickening ratio to a desired value. Illustrative concentrations of base oils, dispersants and viscosity modifiers useful in this disclosure are described more fully hereinbelow.

In a preferred embodiment, a method is provided for improving deposit control and cleanliness performance in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil comprises a lubricating oil base stock as a major component, and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components. The at least one dispersant and the at least one viscosity modifier are present in an amount sufficient to have a critical dispersant thickening ratio of greater than about 0.33. The critical dispersant thickening ratio is determined in accordance with the formula described hereinabove.

In another preferred embodiment, a lubricating oil is provided comprising a lubricating oil base stock as a major component, and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components. The at least one dispersant and the at least one viscosity modifier are present in an amount sufficient to have a critical dispersant thickening ratio of greater than about 0.33. The critical dispersant thickening ratio is determined in accordance with the formula described hereinabove.

The lubricating oils of this disclosure preferably have less than or equal to 1% ash (by mass), more preferably less than or equal to 1% sulfated ash (by mass).

In yet another preferred embodiment, a method is provided for tuning deposit control and cleanliness performance in an engine lubricated with a lubricating oil. The method comprises using as the lubricating oil a formulated oil, said formulated oil comprising a lubricating oil base stock as a major component, and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components; and adjusting the amount of the at least one dispersant and the at least one viscosity modifier sufficient to provide a determined critical dispersant thickening ratio. The critical dispersant thickening ratio is determined in accordance with the formula described hereinabove.

In particular, the amount of the at least one dispersant and the at least one viscosity modifier can be adjusted so as to tune the critical dispersant thickening ratio to a desired value. For example, the amount of the at least one dispersant and the at least one viscosity modifier can be adjusted so as to tune the critical dispersant thickening ratio from a value less than about 0.33 (i.e., low performers as shown in FIG. 1) to a value greater than about 0.33 (i.e., intermediate and high performers as shown in FIG. 1).

In an embodiment, the lubricating oil of this disclosure is a passenger vehicle engine oil (PVEO) or a commercial vehicle engine oil (CVEO).

Examples of techniques that can be employed to characterize the compositions formed by the process described above include, but are not limited to, analytical gas chromatography, nuclear magnetic resonance, thermogravimetric analysis (TGA), inductively coupled plasma mass spectrometry, differential scanning calorimetry (DSC), volatility and viscosity measurements.

Lubricating Oil Base Stocks

A wide range of lubricating oils is known in the art. Lubricating oils that are useful in the present disclosure are both natural oils and synthetic oils. Natural and synthetic oils (or mixtures thereof) can be used unrefined, refined, or rerefined (the latter is also known as reclaimed or reprocessed oil). Unrefined oils are those obtained directly from a natural or synthetic source and used without added purification. These include shale oil obtained directly from retorting operations, petroleum oil obtained directly from primary distillation, and ester oil obtained directly from an esterification process. Refined oils are similar to the oils discussed for unrefined oils except refined oils are subjected to one or more purification steps to improve the at least one lubricating oil property. One skilled in the art is familiar with many purification processes. These processes include solvent extraction, secondary distillation, acid extraction, base extraction, filtration, and percolation. Rerefined oils are obtained by processes analogous to refined oils but using an oil that has been previously used as a feed stock.

Groups I, II, III, IV and V are broad categories of base oil stocks developed and defined by the American Petroleum Institute (API Publication 1509; www.API.org) to create guidelines for lubricant base oils. Group I base stocks generally have a viscosity index of between about 80 to 120 and contain greater than about 0.03% sulfur and less than about 90% saturates. Group II base stocks generally have a viscosity index of between about 80 to 120, and contain less than or equal to about 0.03% sulfur and greater than or equal to about 90% saturates. Group III stock generally has a viscosity index greater than about 120 and contains less than or equal to about 0.03% sulfur and greater than about 90% saturates. Group IV includes polyalphaolefins (PAO). Group V base stocks include base stocks not included in Groups I-IV. Table 1 below summarizes properties of each of these five groups.

TABLE 1 Definition of API Base Oil Groups I, II, III, IV and V Base Oil Properties Saturates Sulfur Viscosity Index Group I <90 and/or >0.03% and ≥80 and <120 Group II ≥90 and ≤0.03% and ≥80 and <120 Group III ≥90 and ≤0.03% and ≥120 Group IV Includes polyalphao efins (PAO) products Group V All other base oil stocks not included in Groups I, II, III or IV

Natural oils include animal oils, vegetable oils (castor oil and lard oil, for example), and mineral oils. Animal and vegetable oils possessing favorable thermal oxidative stability can be used. Of the natural oils, mineral oils are preferred. Mineral oils vary widely as to their crude source, for example, as to whether they are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal or shale are also useful in the present disclosure. Natural oils vary also as to the method used for their production and purification, for example, their distillation range and whether they are straight run or cracked, hydrorefined, or solvent extracted.

Group II and/or Group III hydroprocessed or hydrocracked base stocks, as well as synthetic oils such as polyalphaolefins, alkyl aromatics and synthetic esters, i.e. Group IV and Group V oils are also well known base stock oils.

Synthetic oils include hydrocarbon oil. Hydrocarbon oils include oils such as polymerized and interpolymerized olefins (polybutylenes, polypropylenes, propylene isobutylene copolymers, ethylene-olefin copolymers, and ethylene-alphaolefin copolymers, for example). Polyalphaolefin (PAO) oil base stocks are commonly used synthetic hydrocarbon oil. By way of example, PAOs derived from C8, C10, C12, C14 olefins or mixtures thereof may be utilized. See U.S. Pat. Nos. 4,956,122; 4,827,064; and 4,827,073.

The number average molecular weights of the PAOs, which are known materials and generally available on a major commercial scale from suppliers such as ExxonMobil Chemical Company, Chevron Phillips Chemical Company, BP, and others, typically vary from about 250 to about 3,000, although PAO's may be made in viscosities up to about 150 cSt (100° C.). The PAOs are typically comprised of relatively low molecular weight hydrogenated polymers or oligomers of alphaolefins which include, but are not limited to, C2 to about C32 alphaolefins with the C8 to about C16 alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like, being preferred. The preferred polyalphaolefins are poly-1-octene, poly-1-decene and poly-1-dodecene and mixtures thereof and mixed olefin-derived polyolefins. However, the dimers of higher olefins in the range of C12 to C18 may be used to provide low viscosity base stocks of acceptably low volatility. Depending on the viscosity grade and the starting oligomer, the PAOs may be predominantly dimers, trimers and tetramers of the starting olefins, with minor amounts of the lower and/or higher oligomers, having a viscosity range of 1.5 cSt to 12 cSt. PAO fluids of particular use may include 3 cSt, 3.4 cSt, and/or 3.6 cSt and combinations thereof. Mixtures of PAO fluids having a viscosity range of 1.5 cSt to approximately 150 cSt or more may be used if desired. Unless indicated otherwise, all viscosities cited herein are measured at 100° C.

The PAO fluids may be conveniently made by the polymerization of an alphaolefin in the presence of a polymerization catalyst such as the Friedel-Crafts catalysts including, for example, aluminum trichloride, boron trifluoride or complexes of boron trifluoride with water, alcohols such as ethanol, propanol or butanol, carboxylic acids or esters such as ethyl acetate or ethyl propionate. For example the methods disclosed by U.S. Pat. Nos. 4,149,178 or 3,382,291 may be conveniently used herein. Other descriptions of PAO synthesis are found in the following U.S. Pat. Nos. 3,742,082; 3,769,363; 3,876,720; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355; 4,956,122; and 5,068,487. The dimers of the C₁₄ to C₁₈ olefins are described in U.S. Pat. No. 4,218,330.

Other useful lubricant oil base stocks include wax isomerate base stocks and base oils, comprising hydroisomerized waxy stocks (e.g. waxy stocks such as gas oils, slack waxes, fuels hydrocracker bottoms, etc.), hydroisomerized Fischer-Tropsch waxes, Gas-to-Liquids (GTL) base stocks and base oils, and other wax isomerate hydroisomerized base stocks and base oils, or mixtures thereof. Fischer-Tropsch waxes, the high boiling point residues of Fischer-Tropsch synthesis, are highly paraffinic hydrocarbons with very low sulfur content. The hydroprocessing used for the production of such base stocks may use an amorphous hydrocracking/hydroisomerization catalyst, such as one of the specialized lube hydrocracking (LHDC) catalysts or a crystalline hydrocracking/hydroisomerization catalyst, preferably a zeolitic catalyst. For example, one useful catalyst is ZSM-48 as described in U.S. Pat. No. 5,075,269, the disclosure of which is incorporated herein by reference in its entirety. Processes for making hydrocracked/hydroisomerized distillates and hydrocracked/hydroisomerized waxes are described, for example, in U.S. Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as well as in British Patent Nos. 1,429,494; 1,350,257; 1,440,230 and 1,390,359. Each of the aforementioned patents is incorporated herein in their entirety. Particularly favorable processes are described in European Patent Application Nos. 464546 and 464547, also incorporated herein by reference. Processes using Fischer-Tropsch wax feeds are described in U.S. Pat. Nos. 4,594,172 and 4,943,672, the disclosures of which are incorporated herein by reference in their entirety.

Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and other wax-derived hydroisomerized (wax isomerate) base oils be advantageously used in the instant disclosure, and may have useful kinematic viscosities at 100° C. of about 2 cSt to about 50 cSt, preferably about 2 cSt to about 30 cSt, more preferably about 3 cSt to about 25 cSt, as exemplified by GTL 4 with kinematic viscosity of about 4.0 cSt at 100° C. and a viscosity index of about 141. These Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and other wax-derived hydroisomerized base oils may have useful pour points of about −20° C. or lower, and under some conditions may have advantageous pour points of about −25° C. or lower, with useful pour points of about −30° C. to about −40° C. or lower. Useful compositions of Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and wax-derived hydroisomerized base oils are recited in U.S. Pat. Nos. 6,080,301; 6,090,989, and 6,165,949 for example, and are incorporated herein in their entirety by reference.

The hydrocarbyl aromatics can be used as a base oil or base oil component and can be any hydrocarbyl molecule that contains at least about 5% of its weight derived from an aromatic moiety such as a benzenoid moiety or naphthenoid moiety, or their derivatives. These hydrocarbyl aromatics include alkyl benzenes, alkyl naphthalenes, alkyl biphenyls, alkyl diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides, alkylated bis-phenol A, alkylated thiodiphenol, and the like. The aromatic can be mono-alkylated, dialkylated, polyalkylated, and the like. The aromatic can be mono- or poly-functionalized. The hydrocarbyl groups can also be comprised of mixtures of alkyl groups, alkenyl groups, alkynyl, cycloalkyl groups, cycloalkenyl groups and other related hydrocarbyl groups. The hydrocarbyl groups can range from about C6 up to about C60 with a range of about C8 to about C20 often being preferred. A mixture of hydrocarbyl groups is often preferred, and up to about three such substituents may be present. The hydrocarbyl group can optionally contain sulfur, oxygen, and/or nitrogen containing substituents. The aromatic group can also be derived from natural (petroleum) sources, provided at least about 5% of the molecule is comprised of an above-type aromatic moiety. Viscosities at 100oC of approximately 2 cSt to about 50 cSt are preferred, with viscosities of approximately 3 cSt to about 20 cSt often being more preferred for the hydrocarbyl aromatic component. In one embodiment, an alkyl naphthalene where the alkyl group is primarily comprised of 1-hexadecene is used. Other alkylates of aromatics can be advantageously used. Naphthalene or methyl naphthalene, for example, can be alkylated with olefins such as octene, decene, dodecene, tetradecene or higher, mixtures of similar olefins, and the like. Alkylated naphthalene and analogues may also comprise compositions with isomeric distribution of alkylating groups on the alpha and beta carbon positions of the ring structure. Distribution of groups on the alpha and beta positions of a naphthalene ring may range from 100:1 to 1:100, more often 50:1 to 1:50 Useful concentrations of hydrocarbyl aromatic in a lubricant oil composition can be about 2% to about 25%, preferably about 4% to about 20%, and more preferably about 4% to about 15%, depending on the application.

Alkylated aromatics such as the hydrocarbyl aromatics of the present disclosure may be produced by well-known Friedel-Crafts alkylation of aromatic compounds. See Friedel-Crafts and Related Reactions, Olah, G. A. (ed.), Inter-science Publishers, New York, 1963. For example, an aromatic compound, such as benzene or naphthalene, is alkylated by an olefin, alkyl halide or alcohol in the presence of a Friedel-Crafts catalyst. See Friedel-Crafts and Related Reactions, Vol. 2, part 1, chapters 14, 17, and 18, See Olah, G. A. (ed.), Inter-science Publishers, New York, 1964. Many homogeneous or heterogeneous, solid catalysts are known to one skilled in the art. The choice of catalyst depends on the reactivity of the starting materials and product quality requirements. For example, strong acids such as AlCl3, BF3, or HF may be used. In some cases, milder catalysts such as FeCl3 or SnCl4 are preferred. Newer alkylation technology uses zeolites or solid super acids.

Esters comprise a useful base stock. Additive solvency and seal compatibility characteristics may be secured by the use of esters such as the esters of dibasic acids with monoalkanols and the polyol esters of monocarboxylic acids. Esters of the former type include, for example, the esters of dicarboxylic acids such as phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc., with a variety of alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, etc. Specific examples of these types of esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, etc.

Particularly useful synthetic esters are those which are obtained by reacting one or more polyhydric alcohols, preferably the hindered polyols (such as the neopentyl polyols, e.g., neopentyl glycol, trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylol propane, pentaerythritol and dipentaerythritol) with alkanoic acids containing at least about 4 carbon atoms, preferably C5 to C30 acids such as saturated straight chain fatty acids including caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, and behenic acid, or the corresponding branched chain fatty acids or unsaturated fatty acids such as oleic acid, or mixtures of any of these materials.

Suitable synthetic ester components include the esters of trimethylol propane, trimethylol butane, trimethylol ethane, pentaerythritol and/or dipentaerythritol with one or more monocarboxylic acids containing from about 5 to about 10 carbon atoms. These esters are widely available commercially, for example, the Mobil P-41 and P-51 esters of ExxonMobil Chemical Company.

Also useful are esters derived from renewable material such as coconut, palm, rapeseed, soy, sunflower and the like. These esters may be monoesters, di-esters, polyol esters, complex esters, or mixtures thereof. These esters are widely available commercially, for example, the Mobil P-51 ester of ExxonMobil Chemical Company.

Engine oil formulations containing renewable esters are included in this disclosure. For such formulations, the renewable content of the ester is typically greater than about 70 weight percent, preferably more than about 80 weight percent and most preferably more than about 90 weight percent.

Other useful fluids of lubricating viscosity include non-conventional or unconventional base stocks that have been processed, preferably catalytically, or synthesized to provide high performance lubrication characteristics.

Non-conventional or unconventional base stocks/base oils include one or more of a mixture of base stock(s) derived from one or more Gas-to-Liquids (GTL) materials, as well as isomerate/isodewaxate base stock(s) derived from natural wax or waxy feeds, mineral and or non-mineral oil waxy feed stocks such as slack waxes, natural waxes, and waxy stocks such as gas oils, waxy fuels hydrocracker bottoms, waxy raffinate, hydrocrackate, thermal crackates, or other mineral, mineral oil, or even non-petroleum oil derived waxy materials such as waxy materials received from coal liquefaction or shale oil, and mixtures of such base stocks.

GTL materials are materials that are derived via one or more synthesis, combination, transformation, rearrangement, and/or degradation/deconstructive processes from gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks such as hydrogen, carbon dioxide, carbon monoxide, water, methane, ethane, ethylene, acetylene, propane, propylene, propyne, butane, butylenes, and butynes. GTL base stocks and/or base oils are GTL materials of lubricating viscosity that are generally derived from hydrocarbons; for example, waxy synthesized hydrocarbons, that are themselves derived from simpler gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks. GTL base stock(s) and/or base oil(s) include oils boiling in the lube oil boiling range (1) separated/fractionated from synthesized GTL materials such as, for example, by distillation and subsequently subjected to a final wax processing step which involves either or both of a catalytic dewaxing process, or a solvent dewaxing process, to produce lube oils of reduced/low pour point; (2) synthesized wax isomerates, comprising, for example, hydrodewaxed or hydroisomerized cat and/or solvent dewaxed synthesized wax or waxy hydrocarbons; (3) hydrodewaxed or hydroisomerized cat and/or solvent dewaxed Fischer-Tropsch (F-T) material (i.e., hydrocarbons, waxy hydrocarbons, waxes and possible analogous oxygenates); preferably hydrodewaxed or hydroisomerized/followed by cat and/or solvent dewaxing dewaxed F-T waxy hydrocarbons, or hydrodewaxed or hydroisomerized/followed by cat (or solvent) dewaxing dewaxed, F-T waxes, or mixtures thereof.

GTL base stock(s) and/or base oil(s) derived from GTL materials, especially, hydrodewaxed or hydroisomerized/followed by cat and/or solvent dewaxed wax or waxy feed, preferably F-T material derived base stock(s) and/or base oil(s), are characterized typically as having kinematic viscosities at 100° C. of from about 2 mm2/s to about 50 mm2/s (ASTM D445). They are further characterized typically as having pour points of −5° C. to about −40° C. or lower (ASTM D97). They are also characterized typically as having viscosity indices of about 80 to about 140 or greater (ASTM D2270).

In addition, the GTL base stock(s) and/or base oil(s) are typically highly paraffinic (>90% saturates), and may contain mixtures of monocycloparaffins and multicycloparaffins in combination with non-cyclic isoparaffins. The ratio of the naphthenic (i.e., cycloparaffin) content in such combinations varies with the catalyst and temperature used. Further, GTL base stock(s) and/or base oil(s) typically have very low sulfur and nitrogen content, generally containing less than about 10 ppm, and more typically less than about 5 ppm of each of these elements. The sulfur and nitrogen content of GTL base stock(s) and/or base oil(s) obtained from F-T material, especially F-T wax, is essentially nil. In addition, the absence of phosphorus and aromatics make this materially especially suitable for the formulation of low SAP products.

The term GTL base stock and/or base oil and/or wax isomerate base stock and/or base oil is to be understood as embracing individual fractions of such materials of wide viscosity range as recovered in the production process, mixtures of two or more of such fractions, as well as mixtures of one or two or more low viscosity fractions with one, two or more higher viscosity fractions to produce a blend wherein the blend exhibits a target kinematic viscosity.

The GTL material, from which the GTL base stock(s) and/or base oil(s) is/are derived is preferably an F-T material (i.e., hydrocarbons, waxy hydrocarbons, wax).

Base oils for use in the formulated lubricating oils useful in the present disclosure are any of the variety of oils corresponding to API Group I, Group II, Group III, Group IV, and Group V oils and mixtures thereof, preferably API Group II, Group III, Group IV, and Group V oils and mixtures thereof, more preferably the Group III to Group V base oils due to their exceptional volatility, stability, viscometric and cleanliness features. Minor quantities of Group I stock, such as the amount used to dilute additives for blending into formulated lube oil products, can be tolerated but should be kept to a minimum, i.e. amounts only associated with their use as diluent/carrier oil for additives used on an “as-received” basis. Even in regard to the Group II stocks, it is preferred that the Group II stock be in the higher quality range associated with that stock, i.e. a Group II stock having a viscosity index in the range 100<VI<120.

The base stock component of the present lubricating oils will typically be from 1 to 99 weight percent of the total composition (all proportions and percentages set out in this specification are by weight unless the contrary is stated) and more preferably in the range of 10 to 99 weight percent, or more preferably from 15 to 80 percent, or more preferably from 20 to 70 percent, or more preferably from 25 to 60 percent, or more preferably from 30 to 50 percent.

Dispersants

During engine operation, oil-insoluble oxidation byproducts are produced. Dispersants help keep these byproducts in solution, thus diminishing their deposition on metal surfaces. Dispersants used in the formulation of the lubricating oil may be ashless or ash-forming in nature. Preferably, the dispersant is ashless. So called ashless dispersants are organic materials that form substantially no ash upon combustion. For example, non-metal-containing or borated metal-free dispersants are considered ashless. In contrast, metal-containing detergents form ash upon combustion.

Suitable dispersants typically contain a polar group attached to a relatively high molecular weight hydrocarbon chain. The polar group typically contains at least one element of nitrogen or oxygen. Typical hydrocarbon chains contain 50 to 400 carbon atoms.

A particularly useful class of dispersants are the (poly)alkenylsuccinic derivatives, typically produced by the reaction of a long chain hydrocarbyl substituted succinic compound, usually a hydrocarbyl substituted succinic anhydride, with a polyhydroxy or polyamino compound. The long chain hydrocarbyl group constituting the oleophilic portion of the molecule which confers solubility in the oil, is normally a polyisobutylene group. Many examples of this type of dispersant are well known commercially and in the literature. Exemplary U.S. patents describing such dispersants are U.S. Pat. Nos. 3,172,892; 3,2145,707; 3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012; 3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other types of dispersant are described in U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025; 3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250; 3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082; 5,705,458. A further description of dispersants may be found, for example, in European Patent Application No. 471 071, to which reference is made for this purpose.

Hydrocarbyl-substituted succinic acid and hydrocarbyl-substituted succinic anhydride derivatives are useful dispersants. In particular, succinimide, succinate esters, or succinate ester amides prepared by the reaction of a hydrocarbon-substituted succinic acid compound preferably having at least 50 carbon atoms in the hydrocarbon substituent, with at least one equivalent of an alkylene amine are particularly useful.

Succinimides are formed by the condensation reaction between hydrocarbyl substituted succinic anhydrides and amines. Molar ratios can vary depending on the polyamine. For example, the molar ratio of hydrocarbyl substituted succinic anhydride to TEPA can vary from about 1:1 to about 5:1. Representative examples are shown in U.S. Pat. Nos. 3,087,936; 3,172,892; 3,219,666; 3,272,746; 3,322,670; and 3,652,616, 3,948,800; and Canada Patent No. 1,094,044.

Succinate esters are formed by the condensation reaction between hydrocarbyl substituted succinic anhydrides and alcohols or polyols. Molar ratios can vary depending on the alcohol or polyol used. For example, the condensation product of a hydrocarbyl substituted succinic anhydride and pentaerythritol is a useful dispersant.

Succinate ester amides are formed by condensation reaction between hydrocarbyl substituted succinic anhydrides and alkanol amines. For example, suitable alkanol amines include ethoxylated polyalkylpolyamines, propoxylated polyalkylpolyamines and polyalkenylpolyamines such as polyethylene polyamines. One example is propoxylated hexamethylenediamine. Representative examples are shown in U.S. Pat. No. 4,426,305.

The molecular weight of the hydrocarbyl substituted succinic anhydrides used in the preceding paragraphs will typically range between 800 and 2,500 or more. The above products can be post-reacted with various reagents such as sulfur, oxygen, formaldehyde, carboxylic acids such as oleic acid. The above products can also be post reacted with boron compounds such as boric acid, borate esters or highly borated dispersants, to form borated dispersants generally having from about 0.1 to about 5 moles of boron per mole of dispersant reaction product.

Mannich base dispersants are made from the reaction of alkylphenols, formaldehyde, and amines. See U.S. Pat. No. 4,767,551, which is incorporated herein by reference. Process aids and catalysts, such as oleic acid and sulfonic acids, can also be part of the reaction mixture. Molecular weights of the alkylphenols range from 800 to 2,500. Representative examples are shown in U.S. Pat. Nos. 3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953; 3,798,165; and 3,803,039.

Typical high molecular weight aliphatic acid modified Mannich condensation products useful in this disclosure can be prepared from high molecular weight alkyl-substituted hydroxyaromatics or HNR2 group-containing reactants.

Hydrocarbyl substituted amine ashless dispersant additives are well known to one skilled in the art; see, for example, U.S. Pat. Nos. 3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209, and 5,084,197.

Preferred dispersants include borated and non-borated succinimides, including those derivatives from mono-succinimides, bis-succinimides, and/or mixtures of mono- and bis-succinimides, wherein the hydrocarbyl succinimide is derived from a hydrocarbylene group such as polyisobutylene having a Mn of from about 500 to about 5000, or from about 1000 to about 3000, or about 1000 to about 2000, or a mixture of such hydrocarbylene groups, often with high terminal vinylic groups. Other preferred dispersants include succinic acid-esters and amides, alkylphenol-polyamine-coupled Mannich adducts, their capped derivatives, and other related components.

Polymethacrylate or polyacrylate derivatives are another class of dispersants. These dispersants are typically prepared by reacting a nitrogen containing monomer and a methacrylic or acrylic acid esters containing 5-25 carbon atoms in the ester group. Representative examples are shown in U.S. Pat. Nos. 2, 100, 993, and 6,323,164. Polymethacrylate and polyacrylate dispersants are normally used as multifunctional viscosity modifiers. The lower molecular weight versions can be used as lubricant dispersants or fuel detergents.

Illustrative preferred dispersants useful in this disclosure include those derived from polyalkenyl-substituted mono- or dicarboxylic acid, anhydride or ester, which dispersant has a polyalkenyl moiety with a number average molecular weight of at least 900 and from greater than 1.3 to 1.7, preferably from greater than 1.3 to 1.6, most preferably from greater than 1.3 to 1.5, functional groups (mono- or dicarboxylic acid producing moieties) per polyalkenyl moiety (a medium functionality dispersant). Functionality (F) can be determined according to the following formula:

F=(SAP×Mn)/((112,200×A.I.)−(SAP×98))

wherein SAP is the saponification number (i.e., the number of milligrams of KOH consumed in the complete neutralization of the acid groups in one gram of the succinic-containing reaction product, as determined according to ASTM D94); Mn is the number average molecular weight of the starting olefin polymer; and A.I. is the percent active ingredient of the succinic-containing reaction product (the remainder being unreacted olefin polymer, succinic anhydride and diluent).

The polyalkenyl moiety of the dispersant may have a number average molecular weight of at least 900, suitably at least 1500, preferably between 1800 and 3000, such as between 2000 and 2800, more preferably from about 2100 to 2500, and most preferably from about 2200 to about 2400. The molecular weight of a dispersant is generally expressed in terms of the molecular weight of the polyalkenyl moiety. This is because the precise molecular weight range of the dispersant depends on numerous parameters including the type of polymer used to derive the dispersant, the number of functional groups, and the type of nucleophilic group employed.

Polymer molecular weight, specifically Mn, can be determined by various known techniques. One convenient method is gel permeation chromatography (GPC), which additionally provides molecular weight distribution information (see W. W. Yau, J. J. Kirkland and D. D. Bly, “Modern Size Exclusion Liquid Chromatography”, John Wiley and Sons, New York, 1979). Another useful method for determining molecular weight, particularly for lower molecular weight polymers, is vapor pressure osmometry (e.g., ASTM D3592).

The polyalkenyl moiety in a dispersant preferably has a narrow molecular weight distribution (MWD), also referred to as polydispersity, as determined by the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn). Polymers having a Mw/Mn of less than 2.2, preferably less than 2.0, are most desirable. Suitable polymers have a polydispersity of from about 1.5 to 2.1, preferably from about 1.6 to about 1.8.

Suitable polyalkenes employed in the formation of the dispersants include homopolymers, interpolymers or lower molecular weight hydrocarbons. One family of such polymers comprise polymers of ethylene and/or at least one C3 to C2 alpha-olefin having the formula H2C=CHR1 wherein R1 is a straight or branched chain alkyl radical comprising 1 to 26 carbon atoms and wherein the polymer contains carbon-to-carbon unsaturation, and a high degree of terminal ethenylidene unsaturation. Preferably, such polymers comprise interpolymers of ethylene and at least one alpha-olefin of the above formula, wherein R1 is alkyl of from 1 to 18 carbon atoms, and more preferably is alkyl of from 1 to 8 carbon atoms, and more preferably still of from 1 to 2 carbon atoms.

Another useful class of polymers is polymers prepared by cationic polymerization of monomers such as isobutene and styrene. Common polymers from this class include polyisobutenes obtained by polymerization of a C4 refinery stream having a butene content of 35 to 75% by wt., and an isobutene content of 30 to 60% by wt. A preferred source of monomer for making poly-n-butenes is petroleum feedstreams such as Raffinate II. These feedstocks are disclosed in the art such as in U.S. Pat. No. 4,952,739. A preferred embodiment utilizes polyisobutylene prepared from a pure isobutylene stream or a Raffinate I stream to prepare reactive isobutylene polymers with terminal vinylidene olefins. Polyisobutene polymers that may be employed are generally based on a polymer chain of from 1500 to 3000.

The dispersant(s) are preferably non-polymeric (e.g., mono- or bis-succinimides). Such dispersants can be prepared by conventional processes such as disclosed in U.S. Patent Application Publication No. 2008/0020950, the disclosure of which is incorporated herein by reference.

The dispersant(s) can be borated by conventional means, as generally disclosed in U.S. Pat. Nos. 3,087,936, 3,254,025 and 5,430,105.

Such dispersants may be used in an amount of about 0.01 to 20 weight percent or 0.01 to 10 weight percent, preferably about 0.5 to 8 weight percent, or more preferably 0.5 to 4 weight percent. Or such dispersants may be used in an amount of about 2 to 12 weight percent, preferably about 4 to 10 weight percent, or more preferably 6 to 9 weight percent. On an active ingredient basis, such additives may be used in an amount of about 0.06 to 14 weight percent, preferably about 0.3 to 6 weight percent. The hydrocarbon portion of the dispersant atoms can range from C60 to C1000, or from C70 to C300, or from C70 to C200. These dispersants may contain both neutral and basic nitrogen, and mixtures of both. Dispersants can be end-capped by borates and/or cyclic carbonates. Nitrogen content in the finished oil can vary from about 200 ppm by weight to about 2000 ppm by weight, preferably from about 200 ppm by weight to about 1200 ppm by weight. Basic nitrogen can vary from about 100 ppm by weight to about 1000 ppm by weight, preferably from about 100 ppm by weight to about 600 ppm by weight.

As used herein, the dispersant concentrations are given on an “as delivered” basis. Typically, the active dispersant is delivered with a process oil. The “as delivered” dispersant typically contains from about 20 weight percent to about 80 weight percent, or from about 40 weight percent to about 60 weight percent, of active dispersant in the “as delivered” dispersant product.

Viscosity Modifiers

Viscosity modifiers (also known as viscosity index improvers (VI improvers), and viscosity improvers) can be included in the lubricant compositions of this disclosure.

Viscosity modifiers provide lubricants with high and low temperature operability. These additives impart shear stability at elevated temperatures and acceptable viscosity at low temperatures.

Suitable viscosity modifiers include high molecular weight hydrocarbons, polyesters and viscosity modifier dispersants that function as both a viscosity modifier and a dispersant. Typical molecular weights of these polymers are between about 10,000 to 1,500,000, more typically about 20,000 to 1,200,000, and even more typically between about 50,000 and 1,000,000.

Examples of suitable viscosity modifiers are linear or star-shaped polymers and copolymers of methacrylate, butadiene, olefins, or alkylated styrenes. Polyisobutylene is a commonly used viscosity modifier. Another suitable viscosity modifier is polymethacrylate (copolymers of various chain length alkyl methacrylates, for example), some formulations of which also serve as pour point depressants. Other suitable viscosity modifiers include copolymers of ethylene and propylene, hydrogenated block copolymers of styrene and isoprene, and polyacrylates (copolymers of various chain length acrylates, for example). Specific examples include styrene-isoprene or styrene-butadiene based polymers of 50,000 to 200,000 molecular weight.

Olefin copolymers are commercially available from Chevron Oronite Company LLC under the trade designation “PARATONE®” (such as “PARATONE® 8921” and “PARATONE® 8941”); from Afton Chemical Corporation under the trade designation “HiTEC®” (such as “HiTEC® 5850B”); and from The Lubrizol Corporation under the trade designation “Lubrizol® 7067C”. Hydrogenated polyisoprene star polymers are commercially available from Infineum International Limited, e.g., under the trade designation “SV200”, “SV260”, “SV270” and “SV600”. Hydrogenated diene-styrene block copolymers are commercially available from Infineum International Limited, e.g., under the trade designation “SV 150”.

The polymethacrylate or polyacrylate polymers can be linear polymers which are available from Evnoik Industries under the trade designation “Viscoplex®” (e.g., Viscoplex 6-954) or star polymers which are available from Lubrizol Corporation under the trade designation Asteric™ (e.g., Lubrizol 87708 and Lubrizol 87725).

Illustrative vinyl aromatic-containing polymers useful in this disclosure may be derived predominantly from vinyl aromatic hydrocarbon monomer. Illustrative vinyl aromatic-containing copolymers useful in this disclosure may be represented by the following general formula:

A−B

wherein A is a polymeric block derived predominantly from vinyl aromatic hydrocarbon monomer, and B is a polymeric block derived predominantly from conjugated diene monomer.

In an embodiment of this disclosure, the viscosity modifiers may be used in an amount of less than about 10 weight percent, preferably less than about 7 weight percent, more preferably less than about 4 weight percent, and in certain instances, may be used at less than 2 weight percent, preferably less than about 1 weight percent, and more preferably less than about 0.5 weight percent, based on the total weight of the formulated oil or lubricating engine oil. Viscosity modifiers are typically added as concentrates, in large amounts of diluent oil.

As used herein, the viscosity modifier concentrations are given on an “as delivered” basis. Typically, the active polymer is delivered with a diluent oil. The “as delivered” viscosity modifier typically contains from 20 weight percent to 75 weight percent of an active polymer for polymethacrylate or polyacrylate polymers, or from 8 weight percent to 20 weight percent of an active polymer for olefin copolymers, hydrogenated polyisoprene star polymers, or hydrogenated diene-styrene block copolymers, in the “as delivered” polymer concentrate.

Other Lubricating Oil Additives

The formulated lubricating oil useful in the present disclosure may additionally contain one or more of the commonly used lubricating oil performance additives including but not limited to detergents, corrosion inhibitors, rust inhibitors, metal deactivators, antiwear agents and/or extreme pressure additives, anti-seizure agents, wax modifiers, fluid-loss additives, seal compatibility agents, other friction modifiers, lubricity agents, anti-staining agents, chromophoric agents, defoamants, demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants, and others. For a review of many commonly used additives, see Klamann in Lubricants and Related Products, Verlag Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0. Reference is also made to “Lubricant Additives” by M. W. Ranney, published by Noyes Data Corporation of Parkridge, N.J. (1973); see also U.S. Pat. No. 7,704,930, the disclosure of which is incorporated herein in its entirety. These additives are commonly delivered with varying amounts of diluent oil, that may range from 5 weight percent to 50 weight percent.

All of the additives described below can be used alone or in combination. The total treat rates for the additives can range from 1 to 30 percent, or more preferably from 2 to 25 percent, or more preferably from 3 to 20 percent, or more preferably from 4 to 15 percent, or more preferably from 5 to 10 percent. Particularly preferred compositions have additive levels between 15 and 20 percent.

The additives useful in this disclosure do not have to be soluble in the lubricating oils. Insoluble additives in oil can be dispersed in the lubricating oils of this disclosure.

The types and quantities of performance additives used in combination with the instant disclosure in lubricant compositions are not limited by the examples shown herein as illustrations.

Detergents

Illustrative detergents useful in this disclosure include, for example, alkali metal detergents, alkaline earth metal detergents, or mixtures of one or more alkali metal detergents and one or more alkaline earth metal detergents. A typical detergent is an anionic material that contains a long chain hydrophobic portion of the molecule and a smaller anionic or oleophobic hydrophilic portion of the molecule. The anionic portion of the detergent is typically derived from an organic acid such as a sulfur-containing acid, carboxylic acid (e.g., salicylic acid), phosphorus-containing acid, phenol, or mixtures thereof. The counterion is typically an alkaline earth or alkali metal. The detergent can be overbased as described herein.

The detergent is preferably a metal salt of an organic or inorganic acid, a metal salt of a phenol, or mixtures thereof. The metal is preferably selected from an alkali metal, an alkaline earth metal, and mixtures thereof. The organic or inorganic acid is selected from an aliphatic organic or inorganic acid, a cycloaliphatic organic or inorganic acid, an aromatic organic or inorganic acid, and mixtures thereof.

The metal is preferably selected from an alkali metal, an alkaline earth metal, and mixtures thereof. More preferably, the metal is selected from calcium (Ca), magnesium (Mg), and mixtures thereof.

The organic acid or inorganic acid is preferably selected from a sulfur-containing acid, a carboxylic acid, a phosphorus-containing acid, and mixtures thereof.

Preferably, the metal salt of an organic or inorganic acid or the metal salt of a phenol comprises calcium phenate, calcium sulfonate, calcium salicylate, magnesium phenate, magnesium sulfonate, magnesium salicylate, an overbased detergent, and mixtures thereof.

Salts that contain a substantially stochiometric amount of the metal are described as neutral salts and have a total base number (TBN, as measured by ASTM D2896) of from 0 to 80. Many compositions are overbased, containing large amounts of a metal base that is achieved by reacting an excess of a metal compound (a metal hydroxide or oxide, for example) with an acidic gas (such as carbon dioxide). Useful detergents can be neutral, mildly overbased, or highly overbased. These detergents can be used in mixtures of neutral, overbased, highly overbased calcium salicylate, sulfonates, phenates and/or magnesium salicylate, sulfonates, phenates. The TBN ranges can vary from low, medium to high TBN products, including as low as 0 to as high as 600. Preferably the TBN delivered by the detergent is between 1 and 20. More preferably between 1 and 12. Mixtures of low, medium, high TBN can be used, along with mixtures of calcium and magnesium metal based detergents, and including sulfonates, phenates, salicylates, and carboxylates. A detergent mixture with a metal ratio of 1, in conjunction of a detergent with a metal ratio of 2, and as high as a detergent with a metal ratio of 5, can be used. Borated detergents can also be used.

Alkaline earth phenates are another useful class of detergent. These detergents can be made by reacting alkaline earth metal hydroxide or oxide (CaO, Ca(OH)2, BaO, Ba(OH)2, MgO, Mg(OH)2, for example) with an alkyl phenol or sulfurized alkylphenol. Useful alkyl groups include straight chain or branched C1-C30 alkyl groups, preferably, C4-C20 or mixtures thereof. Examples of suitable phenols include isobutylphenol, 2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the like. It should be noted that starting alkylphenols may contain more than one alkyl substituent that are each independently straight chain or branched and can be used from 0.5 to 6 weight percent. When a non-sulfurized alkylphenol is used, the sulfurized product may be obtained by methods well known in the art. These methods include heating a mixture of alkylphenol and sulfurizing agent (including elemental sulfur, sulfur halides such as sulfur dichloride, and the like) and then reacting the sulfurized phenol with an alkaline earth metal base.

In accordance with this disclosure, metal salts of carboxylic acids are preferred detergents. These carboxylic acid detergents may be prepared by reacting a basic metal compound with at least one carboxylic acid and removing free water from the reaction product. These compounds may be overbased to produce the desired TBN level. Detergents made from salicylic acid are one preferred class of detergents derived from carboxylic acids. Useful salicylates include long chain alkyl salicylates. One useful family of compositions is of the formula

where R is an alkyl group having 1 to about 30 carbon atoms, n is an integer from 1 to 4, and M is an alkaline earth metal. Preferred R groups are alkyl chains of at least C11, preferably C13 or greater. R may be optionally substituted with substituents that do not interfere with the detergent's function. M is preferably, calcium, magnesium, barium, or mixtures thereof. More preferably, M is calcium.

Hydrocarbyl-substituted salicylic acids may be prepared from phenols by the Kolbe reaction (see U.S. Pat. No. 3,595,791). The metal salts of the hydrocarbyl-substituted salicylic acids may be prepared by double decomposition of a metal salt in a polar solvent such as water or alcohol.

Alkaline earth metal phosphates are also used as detergents and are known in the art.

Detergents may be simple detergents or what is known as hybrid or complex detergents. The latter detergents can provide the properties of two detergents without the need to blend separate materials. See U.S. Pat. No. 6,034,039.

Preferred detergents include calcium sulfonates, magnesium sulfonates, calcium salicylates, magnesium salicylates, calcium phenates, magnesium phenates, and other related components (including borated detergents), and mixtures thereof. Preferred mixtures of detergents include magnesium sulfonate and calcium salicylate, magnesium sulfonate and calcium sulfonate, magnesium sulfonate and calcium phenate, calcium phenate and calcium salicylate, calcium phenate and calcium sulfonate, calcium phenate and magnesium salicylate, calcium phenate and magnesium phenate. Overbased detergents are also preferred.

The detergent concentration in the lubricating oils of this disclosure can range from about 0.5 to about 6.0 weight percent, preferably about 0.6 to 5.0 weight percent, and more preferably from about 0.8 weight percent to about 4.0 weight percent, based on the total weight of the lubricating oil.

As used herein, the detergent concentrations are given on an “as delivered” basis. Typically, the active detergent is delivered with a process oil. The “as delivered” detergent typically contains from about 20 weight percent to about 100 weight percent, or from about 40 weight percent to about 60 weight percent, of active detergent in the “as delivered” detergent product.

Antioxidants

Antioxidants retard the oxidative degradation of base oils during service. Such degradation may result in deposits on metal surfaces, the presence of sludge, or a viscosity increase in the lubricant. One skilled in the art knows a wide variety of oxidation inhibitors that are useful in lubricating oil compositions. See, Klamann in Lubricants and Related Products, op cite, and U.S. Pat. Nos. 4,798,684 and 5,084,197, for example.

Useful antioxidants include hindered phenols. These phenolic antioxidants may be ashless (metal-free) phenolic compounds or neutral or basic metal salts of certain phenolic compounds. Typical phenolic antioxidant compounds are the hindered phenolics which are the ones which contain a sterically hindered hydroxyl group, and these include those derivatives of dihydroxy aryl compounds in which the hydroxyl groups are in the o- or p-position to each other. Typical phenolic antioxidants include the hindered phenols substituted with C6+ alkyl groups and the alkylene coupled derivatives of these hindered phenols. Examples of phenolic materials of this type 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful hindered mono-phenolic antioxidants may include for example hindered 2,6-di-alkyl-phenolic proprionic ester derivatives. Bis-phenolic antioxidants may also be advantageously used in combination with the instant disclosure. Examples of ortho-coupled phenols include: 2,2′-bis(4-heptyl-6-t-butyl-phenol); 2,2′-bis(4-octyl-6-t-butyl-phenol); and 2,2′-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenols include for example 4,4′-bis(2,6-di-t-butyl phenol) and 4,4′-methylene-bis(2,6-di-t-butyl phenol).

Effective amounts of one or more catalytic antioxidants may also be used. The catalytic antioxidants comprise an effective amount of a) one or more oil soluble polymetal organic compounds; and, effective amounts of b) one or more substituted N,N′-diaryl-o-phenylenediamine compounds or c) one or more hindered phenol compounds; or a combination of both b) and c). Catalytic antioxidants are more fully described in U.S. Pat. No. 8, 048,833, herein incorporated by reference in its entirety.

Non-phenolic oxidation inhibitors which may be used include aromatic amine antioxidants and these may be used either as such or in combination with phenolics. Typical examples of non-phenolic antioxidants include: alkylated and non-alkylated aromatic amines such as aromatic monoamines of the formula R8R9R10N where R8 is an aliphatic, aromatic or substituted aromatic group, R9 is an aromatic or a substituted aromatic group, and R10 is H, alkyl, aryl or R11S(O)XR12 where R11 is an alkylene, alkenylene, or aralkylene group, R12 is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is 0, 1 or 2. The aliphatic group R8 may contain from 1 to about 20 carbon atoms, and preferably contains from about 6 to 12 carbon atoms. The aliphatic group is a saturated aliphatic group. Preferably, both R8 and R9 are aromatic or substituted aromatic groups, and the aromatic group may be a fused ring aromatic group such as naphthyl. Aromatic groups R8 and R9 may be joined together with other groups such as S.

Typical aromatic amines antioxidants have alkyl substituent groups of at least about 6 carbon atoms. Examples of aliphatic groups include hexyl, heptyl, octyl, nonyl, and decyl. Generally, the aliphatic groups will not contain more than about 14 carbon atoms. The general types of amine antioxidants useful in the present compositions include diphenylamines, phenyl naphthylamines, phenothiazines, imidodibenzyls and diphenyl phenylene diamines. Mixtures of two or more aromatic amines are also useful. Polymeric amine antioxidants can also be used. Particular examples of aromatic amine antioxidants useful in the present disclosure include: p,p′-dioctyldiphenylamine; t-octylphenyl-alpha-naphthylamine; phenyl-alphanaphthylamine; and p-octylphenyl-alpha-naphthylamine.

Sulfurized alkyl phenols and alkali or alkaline earth metal salts thereof also are useful antioxidants.

Preferred antioxidants include hindered phenols, arylamines. These antioxidants may be used individually by type or in combination with one another. Such additives may be used in an amount of about 0.01 to 5 weight percent, preferably about 0.01 to 1.5 weight percent, more preferably zero to less than 1.5 weight percent, more preferably zero to less than 1 weight percent.

Pour Point Depressants (PPDs)

Conventional pour point depressants (also known as lube oil flow improvers) may be added to the compositions of the present disclosure if desired. These pour point depressant may be added to lubricating compositions of the present disclosure to lower the minimum temperature at which the fluid will flow or can be poured. Examples of suitable pour point depressants include polymethacrylates, polyacrylates, polyarylamides, condensation products of haloparaffin waxes and aromatic compounds, vinyl carboxylate polymers, and terpolymers of dialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers. U.S. Pat. Nos. 1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655, 479; 2,666,746; 2,721,877; 2,721,878; and 3,250,715 describe useful pour point depressants and/or the preparation thereof. Such additives may be used in an amount of about 0.01 to 5 weight percent, preferably about 0.01 to 1.5 weight percent.

Antiwear Additives

A metal alkylthiophosphate and more particularly a metal dialkyl dithio phosphate in which the metal constituent is zinc, or zinc dialkyl dithio phosphate (ZDDP) can be a useful component of the lubricating oils of this disclosure. ZDDP can be derived from primary alcohols, secondary alcohols or mixtures thereof. ZDDP compounds generally are of the formula

Zn[SP(S)(OR1)(OR2)]2

where R1 and R2 are C1-C18 alkyl groups, preferably C2-C12 alkyl groups. These alkyl groups may be straight chain or branched. Alcohols used in the ZDDP can be propanol, 2-propanol, butanol, secondary butanol, pentanols, hexanols such as 4-methyl-2-pentanol, n-hexanol, n-octanol, 2-ethyl hexanol, alkylated phenols, and the like. Mixtures of secondary alcohols or of primary and secondary alcohol can be preferred. Alkyl aryl groups may also be used.

Preferable zinc dithiophosphates which are commercially available include secondary zinc dithiophosphates such as those available from for example, The Lubrizol Corporation under the trade designations “LZ 677A”, “LZ 1095” and “LZ 1371”, from for example Chevron Oronite under the trade designation “OLOA 262” and from for example Afton Chemical under the trade designation “HITEC 7169”.

The ZDDP is typically used in amounts of from about 0.3 weight percent to about 1.5 weight percent, preferably from about 0.4 weight percent to about 1.2 weight percent, more preferably from about 0.5 weight percent to about 1.0 weight percent, and even more preferably from about 0.6 weight percent to about 0.8 weight percent, based on the total weight of the lubricating oil, although more or less can often be used advantageously. Preferably, the ZDDP is a secondary ZDDP and present in an amount of from about 0.6 to 1.0 weight percent of the total weight of the lubricating oil.

Seal Compatibility Agents

Seal compatibility agents help to swell elastomeric seals by causing a chemical reaction in the fluid or physical change in the elastomer. Suitable seal compatibility agents for lubricating oils include organic phosphates, aromatic esters, aromatic hydrocarbons, esters (butylbenzyl phthalate, for example), and polybutenyl succinic anhydride. Such additives may be used in an amount of about 0.01 to 3 weight percent, preferably about 0.01 to 2 weight percent.

Antifoam Agents

Anti-foam agents may advantageously be added to lubricant compositions. These agents retard the formation of stable foams. Silicones and organic polymers are typical anti-foam agents. For example, polysiloxanes, such as silicon oil or polydimethyl siloxane, provide antifoam properties. Anti-foam agents are commercially available and may be used in conventional minor amounts along with other additives such as demulsifiers; usually the amount of these additives combined is less than 1 weight percent and often less than 0.1 weight percent.

Inhibitors and Antirust Additives

Antirust additives (or corrosion inhibitors) are additives that protect lubricated metal surfaces against chemical attack by water or other contaminants. A wide variety of these are commercially available.

One type of antirust additive is a polar compound that wets the metal surface preferentially, protecting it with a film of oil. Another type of antirust additive absorbs water by incorporating it in a water-in-oil emulsion so that only the oil touches the metal surface. Yet another type of antirust additive chemically adheres to the metal to produce a non-reactive surface.

Examples of suitable additives include zinc dithiophosphates, metal phenolates, basic metal sulfonates, fatty acids and amines. Such additives may be used in an amount of about 0.01 to 5 weight percent, preferably about 0.01 to 1.5 weight percent.

Friction Modifiers

A friction modifier is any material or materials that can alter the coefficient of friction of a surface lubricated by any lubricant or fluid containing such material(s). Friction modifiers, also known as friction reducers, or lubricity agents or oiliness agents, and other such agents that change the ability of base oils, formulated lubricant compositions, or functional fluids, to modify the coefficient of friction of a lubricated surface may be effectively used in combination with the base oils or lubricant compositions of the present disclosure if desired. Friction modifiers that lower the coefficient of friction are particularly advantageous in combination with the base oils and lube compositions of this disclosure.

Illustrative friction modifiers may include, for example, organometallic compounds or materials, or mixtures thereof. Illustrative organometallic friction modifiers useful in the lubricating engine oil formulations of this disclosure include, for example, molybdenum amine, molybdenum diamine, an organotungstenate, a molybdenum dithiocarbamate, molybdenum dithiophosphates, molybdenum amine complexes, molybdenum carboxylates, and the like, and mixtures thereof. Similar tungsten based compounds may be preferable.

Other illustrative friction modifiers useful in the lubricating engine oil formulations of this disclosure include, for example, alkoxylated fatty acid esters, alkanolamides, polyol fatty acid esters, borated glycerol fatty acid esters, fatty alcohol ethers, and mixtures thereof.

Illustrative alkoxylated fatty acid esters include, for example, polyoxyethylene stearate, fatty acid polyglycol ester, and the like. These can include polyoxypropylene stearate, polyoxybutylene stearate, polyoxyethylene isosterate, polyoxypropylene isostearate, polyoxyethylene palmitate, and the like.

Illustrative alkanolamides include, for example, lauric acid diethylalkanolamide, palmic acid diethylalkanolamide, and the like. These can include oleic acid diethyalkanolamide, stearic acid diethylalkanolamide, oleic acid diethylalkanolamide, polyethoxylated hydrocarbylamides, polypropoxylated hydrocarbylamides, and the like.

Illustrative polyol fatty acid esters include, for example, glycerol mono-oleate, saturated mono-, di-, and tri-glyceride esters, glycerol mono-stearate, and the like. These can include polyol esters, hydroxyl-containing polyol esters, and the like.

Illustrative borated glycerol fatty acid esters include, for example, borated glycerol mono-oleate, borated saturated mono-, di-, and tri-glyceride esters, borated glycerol mono-sterate, and the like. In addition to glycerol polyols, these can include trimethylolpropane, pentaerythritol, sorbitan, and the like. These esters can be polyol monocarboxylate esters, polyol dicarboxylate esters, and on occasion polyoltricarboxylate esters. Preferred can be the glycerol mono-oleates, glycerol dioleates, glycerol trioleates, glycerol monostearates, glycerol distearates, and glycerol tristearates and the corresponding glycerol monopalmitates, glycerol dipalmitates, and glycerol tripalmitates, and the respective isostearates, linoleates, and the like. On occasion the glycerol esters can be preferred as well as mixtures containing any of these. Ethoxylated, propoxylated, butoxylated fatty acid esters of polyols, especially using glycerol as underlying polyol can be preferred.

Illustrative fatty alcohol ethers include, for example, stearyl ether, myristyl ether, and the like. Alcohols, including those that have carbon numbers from C3 to C50, can be ethoxylated, propoxylated, or butoxylated to form the corresponding fatty alkyl ethers. The underlying alcohol portion can preferably be stearyl, myristyl, C11-C13 hydrocarbon, oleyl, isosteryl, and the like.

The lubricating oils of this disclosure exhibit desired properties, e.g., wear control, in the presence or absence of a friction modifier.

Useful concentrations of friction modifiers may range from 0.01 weight percent to 5 weight percent, or about 0.1 weight percent to about 2.5 weight percent, or about 0.1 weight percent to about 1.5 weight percent, or about 0.1 weight percent to about 1 weight percent. Concentrations of molybdenum-containing materials are often described in terms of Mo metal concentration. Advantageous concentrations of Mo may range from 25 ppm to 700 ppm or more, and often with a preferred range of 50-200 ppm. Friction modifiers of all types may be used alone or in mixtures with the materials of this disclosure. Often mixtures of two or more friction modifiers, or mixtures of friction modifier(s) with alternate surface active material(s), are also desirable.

When lubricating oil compositions contain one or more of the additives discussed above, the additive(s) are blended into the composition in an amount sufficient for it to perform its intended function. Typical amounts of such additives useful in the present disclosure are shown in Table 2 below.

It is noted that many of the additives are shipped from the additive manufacturer as a concentrate, containing one or more additives together, with a certain amount of base oil diluents. The weight percent (wt %) indicated in Table 2 below is based on the total weight of the lubricating oil composition.

TABLE 2 Typical Amounts of Other Lubricating Oil Components Approximate Approximate Compound wt % (Useful) wt % (Preferred) Dispersant 0.1-12 0.1-8  Viscosity Modifier 0.1-10 0.1-1  (solid polymer basis) Detergent 0.1-20 0.1-8  Antioxidant 0.1-5   0.1-1.5 Pour Point Depressant 0.0-5  0.01-1.5 (PPD) Anti-foam Agent 0.001-3   0.001-0.15 Antiwear 0.2-3  0.5-1  Inhibitor and Antirust 0.01-5  0.01-1.5

The foregoing additives are all commercially available materials. These additives may be added independently but are usually precombined in packages which can be obtained from suppliers of lubricant oil additives. Additive packages with a variety of ingredients, proportions and characteristics are available and selection of the appropriate package will take the requisite use of the ultimate composition into account.

The following non-limiting examples are provided to illustrate the disclosure.

EXAMPLES

Formulations were prepared as described in FIG. 2. All of the ingredients used herein are commercially available.

The dispersants used in the formulations were polyisobutylsuccinimide/polyamine (PIBSA/PAM, PIB 1300 Mn) borated dispersant having a typical TBN of 26 mgKOH/g, a typical N content of 1.7%, and a typical B content of 0.87% (Dispersant 1); PIBSA/PAM (PIB 1300 Mn) borated dispersant having a typical TBN of 30 mgKOH/g, a typical N content of 1.57%, and a typical B content of 0.77% (Dispersant 2); PIBSA/PAM borated dispersant having a typical N content of 1.19%, and a typical B content of 2.3% (Dispersant 3); PIBSA/PAM dispersant having a typical N content of 1.43% (Dispersant 4); polyisobutenyl bis-succinimide (PIB 2300-2500 Mn) having a typical TBN of 28 mgKOH/g, and a typical N content of 1.2% (Dispersant 5); and PIBSA/PAM (PIB 2300-2500 Mn) dispersant capped with ethylene carbonate and having a typical N content of 1% (Dispersant 6).

The viscosity modifiers used in the formulations were a hydrogenated isoprene star viscosity modifier having a Mw of 567 k as determined by light scattering and a polydispersity index of 1.6 dissolved in a 4 cSt Fischer-Tropsch Group III base stock (Viscosity Modifier 1); a non-dispersant, styrene-isoprene star copolymer viscosity index improver having a Mp of about 825 k (90%), a Mp of about 119 k (10%), and 17% styrene dissolved in a 4 cSt Fischer-Tropsch Group III base stock (Viscosity Modifier 2); a solid styrene-isoprene block copolymer having a Mw of about 106 k, a Mn of about 104 k, and 33% styrene dissolved in a mixture of a 4 cSt Group IV base stock and TMP ester (Viscosity Modifier 3); a non-dispersant, styrene-isoprene star copolymer viscosity index improver having a Mp of about 825 k (90%), a Mp of about 119 k (10%), and 17% styrene dissolved in a 4 cSt hydroprocessed Group III base stock (Viscosity Modifier 4); a hydrogenated isoprene star viscosity modifier having a Mw of 936 k as determined by light scattering and a polydispersity index of 1.7 dissolved in a 100N Group I base stock (Viscosity Modifier 5); a propylene-butylene polymer (random) having a mole ratio in the polymer of 3:1 propylene:butylene dissolved in a 4.5 cSt Group II base stock (Viscosity Modifier 6); a hydrogenated isoprene star viscosity modifier having a Mw of 786 k as determined by light scattering and a polydispersity index of 1.56 dissolved in a 4 cSt Group III base stock (Viscosity Modifier 7); and a hydrogenated isoprene star viscosity modifier having a Mw of 567 k as determined by light scattering and a polydispersity index of 1.6 dissolved in a 6 cSt Group IV base stock (Viscosity Modifier 8).

Base stocks used in the formulations were one or more of a Group I base stock, a Group II base stock, a Group III base stock, a Group IV base stock, a Group V base stock, or mixtures thereof.

Other additives used in the formulations were one or more of an antioxidant, overbased detergent, pour point depressant, corrosion inhibitor, seal compatibility additive, anti-foam agent, inhibitor, anti-rust additive, and friction modifier (ashless).

Testing was conducted for formulations including kinematic viscosity (Kv100) as determined by ASTM D445, mini-rotary viscometer (MRV) test as determined by ASTM D5293, high temperature high shear viscosity (HTHS) as determined by ASTM D4683, and ash content as determined by ASTM D482. The results are set forth in FIG. 2.

Further testing was conducted for formulations using an engine cleanliness test. The engine cleanliness test was a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure. The results are set forth in FIG. 2.

Cleanliness performance was assessed by calculating the critical dispersant thickening ratio as follows: (i) for each dispersant [Gn] in the formulated oil, multiply [Gn] by dV/d[Gn], and sum overall all n of these contributions: Σ[Gn]*dV/d[Gn]; (ii) for each viscosity modifier [Bm] in the formulated oil, multiply [Bm] by dV/d[Bm], and sum over all m of these contributions: Σ[Bm]*dV/d[Bm]; (iii) take the critical dispersant thickening ratio of Σ[Gn]*dV/d[Gn] over Σ[Bm]*dV/d[Bm], and add dispersant and/or remove viscosity modifier from the formulated oil if the critical dispersant thickening ratio is less than 0.33, and a superior passing CEC L78-T-99 test result is desired. The data presented in FIG. 1 shows that above a critical dispersant thickening ratio of 0.47, a strong passing result in the VW TDi2 test is assured, while below a critical dispersant thickening ratio of 0.33, there are cleanliness concerns for the formulation.

PCT and EP Clauses:

1. A method for improving deposit control and cleanliness performance in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil, said formulated oil comprising a lubricating oil base stock as a major component; and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components; wherein the at least one dispersant and the at least one viscosity modifier are present in an amount sufficient to have a critical dispersant thickening ratio of greater than 0.33; wherein the critical dispersant thickening ratio is determined in accordance with the formula:

$\frac{{\Sigma \left\lbrack G_{n} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack G_{n} \right\rbrack}}{{\Sigma \left\lbrack B_{m} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack B_{m} \right\rbrack}}$

wherein [Gn] is the weight percent of each of n dispersants in the formulated oil, [Bm] is the weight percent of each of m viscosity modifiers in the formulated oil, dV/d[Gn] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of n dispersants in the formulated oil, and dV/d[Bm] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of m viscosity modifiers in the formulated oil.

2. The method of clause 1 wherein the amount of the at least one dispersant and the at least one viscosity modifier is sufficient to provide a critical dispersant thickening ratio of greater than 0.33 in a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure.

3. The method of clauses 1 and 2 wherein the critical dispersant thickening ratio is greater than 0.47, or greater than 0.75, or greater than 1.0

4. The method of clauses 1-3 wherein the lubricating oil base stock comprises a Group I base stock, a Group II base stock, a Group III base stock, a Group IV base stock, a Group V base stock, or mixtures thereof.

5. The method of clauses 1-4 wherein the at least one dispersant is an ashless dispersant.

6. The method of clauses 1-5 wherein the at least one dispersant is selected from the group consisting of hydrocarbyl-substituted succinic acid derivatives, hydrocarbyl-substituted succinic anhydride derivatives, succinimides, succinate esters, succinate ester amides, Mannich base adducts derived from a hydrocarbyl-substituted phenol condensed with an aldehyde and an amine, hydrocarbyl-substituted amines, and polymethacrylate or polyacrylate derivatives.

7. The method of clauses 1-6 wherein the at least one viscosity modifier is selected from the group consisting of linear or star-shaped polymers and copolymers of methacrylate, butadiene, olefins, or alkylated styrenes.

8. The method of clauses 1-7 wherein the lubricating oil further comprises one or more of an antioxidant, detergent, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive.

9. The method of clauses 1-8 wherein the lubricating oil base stock is present in an amount from 78 weight percent to 98 weight percent, the dispersant is present in an amount from 0.5 weight percent to 12 weight percent, and the viscosity modifier is present in an amount from 0.5 weight percent to 10 weight percent, based on the total weight of the lubricating oil.

10. A lubricating oil comprising a lubricating oil base stock as a major component; and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components; wherein the at least one dispersant and the at least one viscosity modifier are present in an amount sufficient to have a critical dispersant thickening ratio of greater than 0.33; wherein the critical dispersant thickening ratio is determined in accordance with the formula:

$\frac{{\Sigma \left\lbrack G_{n} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack G_{n} \right\rbrack}}{{\Sigma \left\lbrack B_{m} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack B_{m} \right\rbrack}}$

wherein [Gn] is the weight percent of each of n dispersants in the formulated oil, [Bm] is the weight percent of each of m viscosity modifiers in the formulated oil, dV/d[Gn] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of n dispersants in the formulated oil, and dV/d[Bm] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of m viscosity modifiers in the formulated oil.

11. The lubricating oil of clause 10 wherein the amount of the at least one dispersant and the at least one viscosity modifier is sufficient to provide a critical dispersant thickening ratio of greater than 0.33 in a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure.

12. The lubricating oil of clauses 10 and 11 having a sulfated ash content of less than or equal to 1% by mass.

13. A method for tuning deposit control and cleanliness performance in an engine lubricated with a lubricating oil, said method comprising:

using as the lubricating oil a formulated oil, said formulated oil comprising a lubricating oil base stock as a major component; and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components; and

adjusting the amount of the at least one dispersant and the at least one viscosity modifier sufficient to provide a determined critical dispersant thickening ratio;

wherein the critical dispersant thickening ratio is determined in accordance with the formula:

$\frac{{\Sigma \left\lbrack G_{n} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack G_{n} \right\rbrack}}{{\Sigma \left\lbrack B_{m} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack B_{m} \right\rbrack}}$

wherein [Gn] is the weight percent of each of n dispersants in the formulated oil, [Bm] is the weight percent of each of m viscosity modifiers in the formulated oil, dV/d[Gn] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of n dispersants in the formulated oil, and dV/d[Bm] is the kinematic viscosity (Kv100) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of m viscosity modifiers in the formulated oil.

14. The method of clause 13 wherein the amount of the at least one dispersant and the at least one viscosity modifier is adjusted so as to tune the critical dispersant thickening ratio from a value less than 0.33 to a value greater than 0.33.

15. The method of clauses 13 and 14 wherein the amount of the at least one dispersant and the at least one viscosity modifier is sufficient to provide a critical dispersant thickening ratio of greater than 0.33 in a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure.

All patents and patent applications, test procedures (such as ASTM methods, UL methods, and the like), and other documents cited herein are fully incorporated by reference to the extent such disclosure is not inconsistent with this disclosure and for all jurisdictions in which such incorporation is permitted.

When numerical lower limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated. While the illustrative embodiments of the disclosure have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the disclosure. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present disclosure, including all features which would be treated as equivalents thereof by those skilled in the art to which the disclosure pertains.

The present disclosure has been described above with reference to numerous embodiments and specific examples. Many variations will suggest themselves to those skilled in this art in light of the above detailed description. All such obvious variations are within the full intended scope of the appended claims. 

1. A method for improving deposit control and cleanliness performance in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil, said formulated oil comprising a lubricating oil base stock as a major component; and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components; wherein the at least one dispersant and the at least one viscosity modifier are present in an amount sufficient to have a critical dispersant thickening ratio of greater than 0.33; wherein the critical dispersant thickening ratio is determined in accordance with the formula: $\frac{{\Sigma \left\lbrack G_{n} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack G_{n} \right\rbrack}}{{\Sigma \left\lbrack B_{m} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack B_{m} \right\rbrack}}$ wherein [G_(n)] is the weight percent of each of n dispersants in the formulated oil, [B_(m)] is the weight percent of each of m viscosity modifiers in the formulated oil, dV/d[G_(n)] is the kinematic viscosity (Kv₁₀₀) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of n dispersants in the formulated oil, and dV/d[B_(m)] is the kinematic viscosity (Kv₁₀₀) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of m viscosity modifiers in the formulated oil.
 2. The method of claim 1 wherein the amount of the at least one dispersant and the at least one viscosity modifier is sufficient to provide a critical dispersant thickening ratio of greater than 0.33 in a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure.
 3. The method of claim 1 wherein the critical dispersant thickening ratio is greater than 0.47.
 4. The method of claim 1 wherein the critical dispersant thickening ratio is greater than 0.75.
 5. The method of claim 1 wherein the critical dispersant thickening ratio is greater than 1.0.
 6. The method of claim 1 wherein the lubricating oil base stock comprises a Group I base stock, a Group II base stock, a Group III base stock, a Group IV base stock, a Group V base stock, or mixtures thereof.
 7. The method of claim 1 wherein the at least one dispersant is an ashless dispersant.
 8. The method of claim 1 wherein the at least one dispersant is selected from the group consisting of hydrocarbyl-substituted succinic acid derivatives, hydrocarbyl-substituted succinic anhydride derivatives, succinimides, succinate esters, succinate ester amides, Mannich base adducts derived from a hydrocarbyl-substituted phenol condensed with an aldehyde and an amine, hydrocarbyl-substituted amines, and polymethacrylate or polyacrylate derivatives.
 9. The method of claim 1 wherein the at least one viscosity modifier is selected from the group consisting of linear or star-shaped polymers and copolymers of methacrylate, butadiene, olefins, or alkylated styrenes.
 10. The method of claim 1 wherein the lubricating oil further comprises one or more of an antioxidant, detergent, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive.
 11. The method of claim 1 wherein the lubricating oil base stock is present in an amount from 78 weight percent to 98 weight percent, the dispersant is present in an amount from 0.5 weight percent to 12 weight percent, and the viscosity modifier is present in an amount from 0.5 weight percent to 10 weight percent, based on the total weight of the lubricating oil.
 12. The method of claim 1 wherein the lubricating oil is a passenger vehicle engine oil (PVEO) or a commercial vehicle engine oil (CVEO).
 13. A lubricating oil comprising a lubricating oil base stock as a major component; and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components; wherein the at least one dispersant and the at least one viscosity modifier are present in an amount sufficient to have a critical dispersant thickening ratio of greater than 0.33; wherein the critical dispersant thickening ratio is determined in accordance with the formula: $\frac{{\Sigma \left\lbrack G_{n} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack G_{n} \right\rbrack}}{{\Sigma \left\lbrack B_{m} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack B_{m} \right\rbrack}}$ wherein [G_(n)] is the weight percent of each of n dispersants in the formulated oil, [B_(m)] is the weight percent of each of m viscosity modifiers in the formulated oil, dV/d[G_(n)] is the kinematic viscosity (Kv₁₀₀) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of n dispersants in the formulated oil, and dV/d[B_(m)] is the kinematic viscosity (Kv₁₀₀) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of m viscosity modifiers in the formulated oil.
 14. The lubricating oil of claim 13 wherein the amount of the at least one dispersant and the at least one viscosity modifier is sufficient to provide a critical dispersant thickening ratio of greater than 0.33 in a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure.
 15. The lubricating oil of claim 13 wherein the critical dispersant thickening ratio is greater than 0.47.
 16. The lubricating oil of claim 13 wherein the critical dispersant thickening ratio is greater than 0.75.
 17. The lubricating oil of claim 13 wherein the critical dispersant thickening ratio is greater than 1.0.
 18. The lubricating oil of claim 13 wherein the lubricating oil base stock comprises a Group I base stock, a Group II base stock, a Group III base stock, a Group IV base stock, a Group V base stock, or mixtures thereof.
 19. The lubricating oil of claim 13 wherein the at least one dispersant is an ashless dispersant.
 20. The lubricating oil of claim 13 wherein the at least one dispersant is selected from the group consisting of hydrocarbyl-substituted succinic acid derivatives, hydrocarbyl-substituted succinic anhydride derivatives, succinimides, succinate esters, succinate ester amides, Mannich base adducts derived from a hydrocarbyl-substituted phenol condensed with an aldehyde and an amine, hydrocarbyl-substituted amines, and polymethacrylate or polyacrylate derivatives.
 21. The lubricating oil of claim 13 wherein the at least one viscosity modifier is selected from the group consisting of linear or star-shaped polymers and copolymers of methacrylate, butadiene, olefins, or alkylated styrenes.
 22. The lubricating oil of claim 13 wherein the lubricating oil further comprises one or more of an antioxidant, detergent, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive.
 23. The lubricating oil of claim 13 wherein the lubricating oil base stock is present in an amount from 78 weight percent to 98 weight percent, the dispersant is present in an amount from 0.5 weight percent to 12 weight percent, and the viscosity modifier is present in an amount from 0.5 weight percent to 10 weight percent, based on the total weight of the lubricating oil.
 24. The lubricating oil of claim 13 wherein the lubricating oil is a passenger vehicle engine oil (PVEO) or a commercial vehicle engine oil (CVEO).
 25. A method for tuning deposit control and cleanliness performance in an engine lubricated with a lubricating oil, said method comprising: using as the lubricating oil a formulated oil, said formulated oil comprising a lubricating oil base stock as a major component; and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, as minor components; and adjusting the amount of the at least one dispersant and the at least one viscosity modifier sufficient to provide a determined critical dispersant thickening ratio; wherein the critical dispersant thickening ratio is determined in accordance with the formula: $\frac{{\Sigma \left\lbrack G_{n} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack G_{n} \right\rbrack}}{{\Sigma \left\lbrack B_{m} \right\rbrack}^{*}{dV}\text{/}{d\left\lbrack B_{m} \right\rbrack}}$ wherein [G_(n)] is the weight percent of each of n dispersants in the formulated oil, [B_(m)] is the weight percent of each of m viscosity modifiers in the formulated oil, dV/d[G_(n)] is the kinematic viscosity (Kv₁₀₀) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of n dispersants in the formulated oil, and dV/d[B_(m)] is the kinematic viscosity (Kv₁₀₀) increase of the lubricating oil as determined by ASTM D445 per the weight percent of each of m viscosity modifiers in the formulated oil.
 26. The method of claim 25 wherein the amount of the at least one dispersant and the at least one viscosity modifier is adjusted so as to tune the critical dispersant thickening ratio from a value less than 0.33 to a value greater than 0.33.
 27. The method of claim 25 wherein the amount of the at least one dispersant and the at least one viscosity modifier is sufficient to provide a critical dispersant thickening ratio of greater than 0.33 in a direct injection, ring sticking (rings 1 and 2), and piston cleanliness test using a Volkswagen TDI2 test engine, in accordance with CEC L78-T-99 test procedure.
 28. The method of claim 25 wherein the critical dispersant thickening ratio is greater than 0.47.
 29. The method of claim 25 wherein the critical dispersant thickening ratio is greater than 0.75.
 30. The method of claim 25 wherein the critical dispersant thickening ratio is greater than 1.0.
 31. The method of claim 25 wherein the lubricating oil base stock comprises a Group I base stock, a Group II base stock, a Group III base stock, a Group IV base stock, a Group V base stock, or mixtures thereof.
 32. The method of claim 25 wherein the at least one dispersant is an ashless dispersant.
 33. The method of claim 25 wherein the at least one dispersant is selected from the group consisting of hydrocarbyl-substituted succinic acid derivatives, hydrocarbyl-substituted succinic anhydride derivatives, succinimides, succinate esters, succinate ester amides, Mannich base adducts derived from a hydrocarbyl-substituted phenol condensed with an aldehyde and an amine, hydrocarbyl-substituted amines, and polymethacrylate or polyacrylate derivatives.
 34. The method of claim 25 wherein the at least one viscosity modifier is selected from the group consisting of linear or star-shaped polymers and copolymers of methacrylate, butadiene, olefins, or alkylated styrenes.
 35. The method of claim 25 wherein the lubricating oil further comprises one or more of an antioxidant, detergent, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive.
 36. The method of claim 25 wherein the lubricating oil base stock is present in an amount from 78 weight percent to 98 weight percent, the dispersant is present in an amount from 0.5 weight percent to 12 weight percent, and the viscosity modifier is present in an amount from 0.5 weight percent to 10 weight percent, based on the total weight of the lubricating oil.
 37. The method of claim 25 wherein the lubricating oil is a passenger vehicle engine oil (PVEO) or a commercial vehicle engine oil (CVEO).
 38. The lubricating oil of claim 13 having a sulfated ash content of less than or equal to 1% by mass. 